Fw: RE: [HBR] Restoration info

[DW Holtman]

Kees,

So you are basicly talking about home brewing a 2-B. That is some serious 
mods. Major re-work. My hat is off to you. I would be VERY interested in how 
it comes out. If you document, please make it available. I have a schematic 
of one around somewhere. I would like to see what you are doing, and know 
how it comes out.

Best,
DW Holtman


----- Original Message ----- 
From: <windy10605 at juno.com>
To: <hbr at mailman.qth.net>
Sent: Wednesday, July 27, 2005 8:29 PM
Subject: Fw: Re: Fw: RE: [HBR] Restoration info


> Thanks for the first input.
>
> I have noticed that there are very few mods available for the 2B which
> may be an indication of how well it was designed.
>
> So far we've come up with the following:
>
> 1) get the 2BQ "Q" multiplier feature to go with the radio
> 2) replace the four .01mfd paper caps on general principle. Replace the
>    electrolytics too. Check "the usual suspects".
> 3) replace the 1mfd AVC paper cap with a 1.5mfd Mylar
> 4) replace the .005 mfd audio coupling cap with a .01mfd Mylar
> 5) replace the 6U8 with a 6EA8
> 6) replace the 6BF6 with a 6AV6 (make sure the leakage is EXTREMELY low)
> 7) since the AVC is Hi-Z you must use a 10Meg+ impedance meter and you
>    will still be 10-15% off on your bias voltage measurements. A 1000Meg
>    input Fluke is OK.
> 8) there is something not right about the audio feedback circuit design
> 9) would like to see more ceramic switches and higher "Q" coils in the
> frontend
> 10) noise limiter can stand more improvement
> 11) BNC antenna connector
> 12) carefull look at dual use tubes for interference
> 13) separate BFO function from Product Detector function in 6BE6 ?
> 14) find better RF amp tube than a 6BZ6
> 15) look into use of pullen mixers
> 16) add a second .005mfd cap across the BFO divider into the 6BF6 cathode
>      to increase the BFO signal level.
>
> 73 Kees K5BCQ
>
>
> --------- Forwarded message ----------
> From: "DW Holtman" <future212 at comcast.net>
> To: "HBR Receiver List" <hbr at mailman.qth.net>
> Date: Wed, 27 Jul 2005 19:53:50 -0600
> Subject: Re: Fw: RE: [HBR] Restoration info
> Message-ID: <001f01c59317$33954a80$61c3b643 at dw2q2am1a08eq5>
> References: <20050727.203458.1864.4.windy10605 at juno.com>
>
> Kees,
>
> I have had several 2-B over the years. I really don't think you are going
> to
> make much improvment in such things as Receiver sensivity, noise floor,
> selectivity ( without adding crystal filters). If I was going to try to
> improve on a 2-b, I might build a digital VFO using DDS technology. You
> would have a very nice 1.5 to 30 MHZ  shortwave receiver. For what it is
> worth.
>
> Best,
> DW Holtman
>
>
>
> ----- Original Message ----- 
> From: <windy10605 at juno.com>
> To: <hbr at mailman.qth.net>
> Sent: Wednesday, July 27, 2005 7:34 PM
> Subject: Fw: Fw: RE: [HBR] Restoration info
>
>
>> It's a 100 page Word document which I will distribute via email once I
>> get a list of names together. You can print it or file it as you wish.
> I
>> also have the 80 or so page RSGB Receiver document by G2DAF as a Word
>> document for those interested. They are both on my CD but occupy too
> much
>> space on the web site. They are both great pieces of info to have if
> you
>> are working on quality tube receivers.
>>
>> Right now, a friend of mine and I are working to improve the Drake 2B
>> receiver. Triple conversion without the typical string of IF stages. If
>> you can find one cheap, buy it. I've always thought the 2B was a great
>> example of a commercial tube type HF receiver of the early 60s
> timeframe
>> which is physically compact, sensitive (0.5uV or better), selective
> (good
>> permeability tuned passband), simple slide switches, multiple Hi-Z AVC
>> points, copper plate chassis (there are no "bad grounds" to tube
>> sockets), screws vs rivets, low power (less than 40W), "low" voltage
>> (less than 180VDC) and uniquely efficient design (have you seen the
>> outstanding use of vertical terminal strips ? super simple graticule
>> adjustment, etc). It also offers the distinct "ease of use" advantage
> of
>> bandswitching and crystal converters. Still an excellent design in this
>> day and age. Maybe some of you have some input on improving that design
> ?
>>
>>
>> 73 Kees K5BCQ
>> ************************************
>> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>> construction notes...... via http://www.qsl.net/k5bcq/
>> there is also a mirror (faster response)at http://k5bcq.edebris.com/
>>
>>
>> Retrieve reflector archived data via
>> http://mailman.qth.net/mailman/listinfo/hbr
>>
>>
>
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
> there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
> Retrieve reflector archived data via
> http://mailman.qth.net/mailman/listinfo/hbr
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
> there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
> Retrieve reflector archived data via 
> http://mailman.qth.net/mailman/listinfo/hbr
>
>